Abnormal Coronary Flow Velocity Reserve After Coronary Artery Stenting in Patients

Abstract

Background —Absolute coronary flow velocity reserve (CVR) after stenting may remain abnormal as a result of several different mechanisms. Relative CVR (rCVR=CVR target /CVR reference ) theoretically normalizes for global microcirculatory disturbances and facilitates interpretation of abnormal CVR. Methods and Results —To characterize potential mechanisms of poststent physiology, CVR was measured using a Doppler-tipped angioplasty guidewire in 55 patients before and after angioplasty, after stenting, and in an angiographically normal reference vessel. For the group, the percent diameter stenosis decreased from 75±13% to 40±18% after angioplasty and to 10±9% (all P <0.05) after stent placement. After angioplasty, CVR increased from 1.63±0.71 to 1.89±0.55 ( P <0.05) and after stent placement, to 2.48±0.75 ( P <0.05 versus pre- and postangioplasty). After angioplasty, rCVR increased from 0.64±0.26 to 0.75±0.23 and after stent placement to 1.00±0.34. In 17 patients with CVR stent ≤2.0, increased basal coronary flow, rather than attenuated hyperemia, was responsible in large part for the lower CVR stent compared with patients having CVR stent >2.0. In 8 patients with CVR stent <2.0, a normal rCVR supported global microvascular disease. The subgroup of 9 patients with CVR stent <2.0 and abnormal rCVR (16% of the studied patients) may require a pressure-derived fractional flow reserve to differentiate persistent obstruction from diffuse atherosclerotic disease or microvascular stunning. Conclusions —Although a majority of patients after stenting normalize CVR for the individual circulation (ie, normal CVR or normal rCVR), in those with impaired CVR stent , the analysis of coronary flow dynamics suggests several different physiological mechanisms. Additional assessment may be required to fully characterize the physiological result for such patients to exclude remediable luminal abnormalities.